You know that age-old debate about whether dogs are smarter than cats? Well, science now has a definitive answer. It's dogs. That's the conclusion of an international team of researchers, who found that dogs possess twice the number of neurons than cats. Neurons are cells that process information. And so, the more neurons an animal has, the better its information processing capability, these scientists say.

The study was conducted by researchers from six universities in the US, Brazil, Denmark and South Africa. It's been accepted for publication in the journal Frontiers in Neuroanatomy. The research was done in the lab of Suzana Herculano-Houzel, an associate professor of psychology and biological sciences at Vanderbilt University.

When scientists looked at cats' and dogs' cerebral cortex, the information-processing part of the brain: A cat's cerebral cortex has 250 million neurons. A 15-pound mixed-breed dog has 429 million. When they looked at a 64-pound golden retriever, the count was even higher: 627 million neurons. "It is fair to say, then, that dogs have about twice as many neurons as cats in their cerebral cortex," she said. "And this implies that dogs have more cognitive capabilities than cats."